What is Perry Directional Porting?  What's it's history, and what does it do?  Anyone got explanatory pictures?  Is it related to Perry carbs?

I remember it being touted on engines that I couldn't hope to afford back in the late '70's, but that's all I know about it.

PDP porting was  sort of a  ripoff of Dr Schnuerle's  porting arrangement, it added  4 very small ports, 2 in the front and  2 in the back, in the  same place a standard loop charged port would go, Boosting  the performance of the single bypass arrangement

Randy

Confusers awry , Read the second page here , save me rattling on . http://www.sceptreflight.net/Model%20Engine%20Tests/ST%20G60%20FI%20ABC-PDP.html

They aim to blow the incoming charge aft , so it doesnt disapear out the zorst ol;e .

I've allways thought that main idea of them ports is to clean away the used gases that would otherwise stay stuck in the turbulence behind piston baffle.

    There is no piston baffle on a Perry ported engine (flat top).  Think of it as three water hoses aiming at each other and meeting in the middle. Most engines have the side ports open first, to block the path of the rear port fuel charge opposite the exhaust and send it up to the combustion chamber, not out the exhaust.
Al.

    There is no piston baffle on a Perry ported engine (flat top).  Think of it as three water hoses aiming at each other and meeting in the middle. Most engines have the side ports open first, to block the path of the rear port fuel charge opposite the exhaust and send it up to the combustion chamber, not out the exhaust.
Al.

PDP were born to improve the scavengig conditions.
The various engine manufacturers have used them with baffle pistons, Supertigre porting (flat top) , with the only purpose of improving engine operating conditions.

Massimo

The Perry in question developed and made carbs for K&B/Veco and at roughly the same time, developed the PDP deal. They had a name like "Perry Automotive" or something like that. Seems to me like K&B may have been first to use PDP, but Super Tigre and HB (not HP) for sure used it. Possibly also Irvine or Webra as well, but I'm not that familiar with either brand. I have two HB .61's, one PDP and one not. Irvine started out as a K&B derivative, and I seem to recall that HB may have been also. "HB" was short for "Helmut Bernhardt" or somewhere close to that.   

I had a Big Jim Greenaway PDP ST .60, and I wondered if Jim might have plugged the PDP ports with JB Weld or something, but never looked. I would expect he at least tried it.  Steve